You may be somewhat surprised to learn that her voice actress is actually Japanese. (And notably an English university major, but that doesn't say much about how clear or fluent her English actually is.)

>>115351197
Toyama Nao's understanding of the english language is one of the best amongst seiyuu right now. At least when it comes to reading and listening, she can pretty much understand the vast majority of it. Her weakness (which is also mostly the case with any non-native english speaker) is being able to speak it herself in person which constantly requires you to think and structure sentences on the fly. Even so, her pronunciation is still decently good and better than a lot of other VAs.

>>115350630
I'm going to let you in on a little secret OP. Anime is actually aimed at Nips, the majority of which likely have even less of a grasp on the English language than her voice actor. Thus they don't need to have her speak with a convincing English accent because the viewers wouldn't be able to tell the difference anyways.